This application hereby claims priority under 35 U.S.C. xc2xa7119 on German Patent Application DE 10149019.4, filed Sep. 28, 2001, the entire contents of which are herein incorporated by reference.
The invention generally relates to an arc quenching device for an air-switching low-voltage switching device, having a quenching chamber which has quenching plates and having a cover. The cover covers the quenching chamber and is provided with outlet openings for switching gases, as well as having an optionally usable, separate cooling device, which has deionization technology, for the switching gases.
Air-switching low-voltage switching devices, such as low-voltage circuit breakers, require, for operation, an arc quenching device, in the form of quenching chambers for cooling and quenching switching arcs, which occur when the contacts separate. In order to prevent any adverse effect on the circuit breaker itself or on adjacent system parts or other assemblies, the switching arcs must be kept away from other components in the circuit breaker, and the hot and thus ionized switching gases must be cooled sufficiently, before they emerge from the quenching chamber, so that no electrical flashovers or other damage occur or occurs in the vicinity of the switching device. Every arc quenching chamber normally contains a large number of quenching plates, which are arranged between two side walls and contribute to the cooling and quenching of the arc. A cover with outlet openings for switching gases is located above the quenching plates.
The locations in which low-voltage circuit breakers are stored may differ widely. This governs the temperature and the extent of ionization that the switching gases which emerge from the arc quenching devices may have. In order to take account of these different conditions, arc quenching devices are produced in a normal version for standard requirements and, if required, may have a separate cooling device for the switching devices added to them. In this case, it is possible for a requirement for improved cooling of the switching gases to be discovered only after a switchgear assembly is installed, for example on the basis of a change in the method of operation or as a result of the use of different loads, with the result that switching operations occur at a higher power level, and with a correspondingly greater amount of switching gases.
According to DE 35 41 514 C2, the additional cooling device includes an attachment for each of the quenching chambers in a circuit breaker. Each attachment has a frame-like housing body and deionization technology, arranged in this housing body, in the form of wire mesh, quenching plates or the like. The advantage of simple retrospective fitting of such a separate cooling device must be traded off against the height of the circuit breaker being increased by the separate cooling device. It is thus possible for a situation to occur in which separate cooling devices cannot be fit retrospectively, because there is insufficient space in the switchgear cubicle.
An object of an embodiment of the invention is to provide an arc quenching device having an additional cooling device which can be installed when required and which does not increase the physical volume of the circuit breaker.
According to an embodiment of present invention, the object is achieved in that a separate cooling device is in the form of a frame for accommodating deionization technology and may be designed to be suitable for installation in the interior of the arc quenching device, between the quenching plates and the cover, with the quenching plates and the cover being supported by common, parallel insulating walls.
It is already known from DE 298 07 119 U1 for a cooling device, which is referred to as a damping insert, for switching gases to be arranged in the space between a arc splitter stack and a quenching chamber cover. This damping insert is held on the cover by way of a screw which connects two cover parts, which can move relative to one another, and contains the female thread for the screw. The relevant arc quenching device can thus not be used without the cooling device. In contrast, on the basis of an embodiment of the invention, arc quenching devices may optionally be used with or without a separate cooling device.
For the purposes of an embodiment of the invention, the cooling device may have a covering panel and a base panel added to it to form an insert cartridge, which forms a cavity for the introduction of the deionization technology, with aperture openings for the switching gases being provided in the covering panel and in the base panel. This configuration results in the cooling device being in a form which is suitable for retrofitting as required. At the same time, this form offers the capability to influence the cooling effect independently of the deionization technology, which are provided, by way of example, in the form of metal meshes or metal sieves. This may be done by the aperture openings having a circular or polygonal cross section, or by them being in the form of slots.
The fitting of the cooling device can be further assisted by the cooling device as well as the cover of the arc quenching device being provided with interacting attachment devices on their side facing the quenching plates, and by the cooling device being fit to the inside of the cover, by way of the attachment devices, if required before the cover is installed on the arc quenching device. Interlocking attachment devices are suitable in a preferred manner for this purpose, for example in such a way that the attachment devices are in the form of holding openings in the cover of the arc quenching device and attachment pins, which are arranged on the covering panel of the insert cartridge and are intended for insertion into said holding openings. In this case, the dimensions of the holding openings and of the attachment pins are expediently matched to one another such that, when the attachment pins are inserted into the holding openings, a friction fit is produced in order to secure them against sliding out. This can be achieved by the attachment devices for producing the friction lock being slotted and sprung.
The attachment devices for the cooling device may also be in the form of molded attachments and guide rails, which originate from them, for insertion of the cooling device, which is in the form of an insert cartridge.
As already mentioned, DE 298 07 119 U1, discloses a method of construction for arc quenching devices, in which the quenching plates are arranged between parallel insulating walls and are attached to them, such that a cohesive arc splitter stack is formed. This method of construction is also suitable for arc quenching devices according to the invention, in which case it has been found to be advantageous for the quenching plates and the cover to be attached to common insulating panels, which are arranged parallel to one another and hold the quenching plates and the cover between them, with webs which point outward being arranged on molded attachments on the cover, and slots which hold the webs being arranged in the insulating panels. This ensures that intended distances are maintained between the ends of the quenching plates, the cooling device and the cover at all times, and thus at the same time ensuring the flow resistance for switching gases and other important parameters.